Long-term observation of coral reefs indicate rising sea levels “not only promoted coral cover” but also “limit damaging effects of thermally-induced bleaching”
B. E. Brown, R. P. Dunne, P. J. Somerfield, A. J. Edwards, W. J. F. Simons,
N. Phongsuwan, L. Putchim, L. Anderson & M. C. Naeije. Long-term impacts of rising sea temperature and sea level on shallow water coral communities over a ~40 year period. Scientific Reports, volume 9, 2019
Effects of combined rising sea temperature and increasing sea level on coral reefs, both factors associated with global warming, have rarely been addressed. In this ~40 y study of shallow reefs in the eastern Indian Ocean, we show that a rising relative sea level, currently estimated at ~11 mm y−1, has not only promoted coral cover but also has potential to limit damaging effects of thermally-induced bleaching. In 2010 the region experienced the most severe bleaching on record with corals subject to sea temperatures of >31 °C for 7 weeks. While the reef flats studied have a common aspect and are dominated by a similar suite of coral species, there was considerable spatial variation in their bleaching response which corresponded with reef-flat depth. Greatest loss of coral cover and community structure disruption occurred on the shallowest reef flats. Damage was less severe on the deepest reef flat where corals were subject to less aerial exposure, rapid flushing and longer submergence in turbid waters. Recovery of the most damaged sites took only ~8 y. While future trajectories of these resilient reefs will depend on sea-level anomalies, and frequency of extreme bleaching the positive role of rising sea level should not be under-estimated.
“The IPCC’s latest serve of climate catastrophism, released just before the UN General Assembly met in New York last month, ironically contained some good news; but not even “inadequate” models, “limited” observations, poor understanding, dodgy “projections” and revelations about “deep uncertainty” could rein in the hyperbole.” click here
“Fears of apocalyptic sea-level rise are nothing new despite the fact that they seem to have recently taken on a new life of their own, especially in South Florida, where I live.
The only scientific correlation I can make with any certainty is that these fears rise in direct proportion to the number of socialists elected to Congress.” click here
Megan E. Tuck, Paul S. Kench, Murray R. Ford, Gerd Masselink. Physical modelling of the response of reef islands to sea-level rise. Geology (2019), https://doi.org/10.1130/G46362.1
“Sea-level rise and increased storminess are expected to destabilize low-lying reef islands formed on coral reef platforms, and increased flooding is expected to render them uninhabitable within the coming decades. Such projections are founded on the assumption that islands are geologically static landforms that will simply drown as sea-level rises. Here, we present evidence from physical model experiments of a reef island that demonstrates islands have the capability to morphodynamically respond to rising sea level through island accretion. Challenging outputs from existing models based on the assumption that islands are geomorphologically inert, results demonstrate that islands not only move laterally on reef platforms, but overwash processes provide a mechanism to build and maintain the freeboard of islands above sea level. Implications of island building are profound, as it will offset existing scenarios of dramatic increases in island flooding. Future predictive models must include the morphodynamic behavior of islands to better resolve flood impacts and future island vulnerability.” click here
For more discussion click here.
Sergey V. Samsonov, Kristy F. Tiampo, Wanpeng Feng. Fast subsidence in downtown of Seattle observed with satellite radar, Remote Sensing Applications: Society and Environment, Volume 4, October 2016, Pages 179-187
Abrupt change in the long term displacement trend was observed in the downtown of Seattle (Washington, USA) with the satellite Differential Interferometric Synthetic Aperture Radar (DInSAR). The forty nine ascending and forty six descending RADARSAT-2 Spotlight SAR images with range-azimuth resolution of 1.6×0.8 m and ground coverage of 18×8 km were collected during June 6, 2012–August 16, 2015. The vertical deformation time series were computed from the ascending and descending data sets with the advanced Multidimensional Small Baseline Subset (MSBAS) software. During June 6, 2012–August 31, 2014 subsidence occurred along the two transportation routes, running north-south parallel to the coast line, reaching 2.5 cm. The long term deformation rate did not exceed 1.2 cm/year and was nearly constant during that time. After August 31, 2014, rapid subsidence appeared in the downtown of Seattle, in a region where it previously was not observed. Over the next four months during August 31, 2014–December 29, 2014 cumulative subsidence reached approximately 2.5 cm, which corresponds to an annual rate of 10 cm/year, about eight times faster than during the previous two years. The rate of subsidence remained high for an additional few months before converging to its secular value. The cause of subsidence was linked to the recent anthropogenic activities related to tunnel boring for Alaskan Way Viaduct replacement project. The elliptical model for subsidence due to groundwater pumping proposed by Tiampo et al. (2012) was used to invert for the physical parameters of the associated groundwater pumping. The results are in good accordance with the location of pumping operations and the groundwater bearing strata in the region. Over a long period of time such fast subsidence will cause additional strain on urban infrastructure, particularly older, historic structures and high-rise buildings. This work provides an excellent example of the importance and applicability of rapid, accurate monitoring of ongoing, large infrastructure projects using DInSAR techniques in order to make optimal use of limited resources and perform early intervention and mitigation strategies.
“TIME titled it’s Thursday cover story, “Our Sinking Planet.” There’s just one problem: Scientific studies show Tavalu’s islands, indeed most Pacific islands, have actually grown in the face of sea level rise.” click here